Vehicle signal circuit



Jan. 9, 1940. H. E. M ETCALF 2,186,766

v VEHICLE SIGNAL CIRCUIT Filed March 19, 1938 2 Sheets-Sheet 1 L 9 v .8R

5 1 L 1 20 R 8' v /9 INVENTOR. HERBERT E. METCALF- H. E. METCALF VEHICLESIGNAL CIRCUIT Filed March 19, 1938 2 Sheets-Sheet 2 AUTOMATIC SWITCHLEFT :1 L MANUAL SWITCH LEFT AUTOMATIC SWITCH 7 LEFT INVENTORT HERBERTE. ME TCALF.

A TTORNEYS.

Patented Jan. 9, 1940 UNITED STATES VEHICLE SIGNAL omooir Herbert E.Metcalfi Walnut Creek, Califi, as-

signor, by mesne assignments, to Signacator Systems, Inc, Oakland,'( 3'alif., ajcorporation of California Application Mareh19, 1938, serial No.196,925 2 Claims. 01. 177-339) My invention relates to vehicle signalcircuits, and more particularly to such a circuit wherein an automaticswitch and a hand switch are utilized' to energize the same signallingindicators, the broad idea of such a combination being described andclaimed in the Clarence B. Howard application for United States LettersPatent entitled Vehicle direction indicator, Serial No. 136,709, filedApril 14., 1937, since matured into United States Patent No. 2,111,931,dated March 22, 1938.

In the Howard application cited above, an automatic switch attached tothe steering gear of a vehicle energized right and left signallingcircuits having signalling indicators therein. A

hand switch was also used to directly. energize the same circuits andindicators in parallel with the automatic switch. The automatic switchwas made to hold in contact making position by the use of anelectromagnet, and the hold was released by passage of current through abucking coil creating a fluxin the opposite direction to that of theholding flux, thus releasing the hand switch upon passage of any currentthrough the automatic switch.

The present application deals with a signalling circuit utilizing anautomatic switch and a hand switch, wherein the hand switch ismechanically held in circuit making position, and an electromagnet isused in the automatic switch circuit to release the mechanical hold. Inthe prior application of Howard referred to, two coils were uti-'-'lized, one in series with the hand switch for holding, and one in serieswith the automatic switch for releasing, whereas the'circuit of myinvention herein to be described and claimed utilizes only a single coilinseries with the automatic switch for causing release.

The main object of the present invention is to provide, with such asystem utilizing only a single release coil, means for properlyapportioning current through the hand switch and through the releasecoil and automatic switch when the indicators on the same side of thevehicle are being simultaneously energized by both switches.

Other objects of my invention will be apparent or will be specificallypointed out in the description forming a part of this specification, butI do not limit myself to the embodiment of the in- 5o vention hereindescribed, asvarious forms may switches when no current is being passedthrough Referring directly to Fig. l, which shows the 1 0 condition ofone preferred circuit embodying my invention when a vehicle isproceeding straight ahead with no signal needed, numeral represents thesteering gear of an automobile. An extension shaft: 2 is attachedthereto in any con- 15' venient'manner, this shaft rotating an automaticswitch" disc 3 carrying a movable segment 4. Movable segment 4 is inconstant contact with a common automatic brush 5, and spaced to rightand left of movable segment 4 are right and left 2 signal circuitbrushes 6 and l respectively. Contactsegment 4 is of insufficient lengthto bridge brushes 6 and i when in the central or straightahead positionof steering gear I but when steering gear l is turned, will bridgecommon brush 5 with "either circuit brush 6 or 'i to signal a vehicleturn; Right and left signal brushes 6 and 'i are connected to right andleft signal lamps 8 and 9 respectively, preferably two lamps showing tothe front and rear of a vehicle. automatic brush 5 is connected throughrelease coil lilvto vehicle battery ii, or similar source. Thus, it willbe seen, with the circuit so far described, upon every turn away fromthe straightaway, vehicle lamps 8 and 9 will be energized I2 rotated byhandle I 4 and centralized in central position by centering springs it.In this position a manual sector it, of conductive material, is incontact with a manual common brush i1. At each side of manual sector itare positioned manual circuit brushes l3 and i9 45 respectively,connected to lamps 8 and 9. Manual common brush I1 is connected tosource I! through abalancing resistor 20. When handle 14 ismoved eitherto right or left, sector it moves and makes electrical connectionbetween .56 manual common brush H and manual circuit brushes [8 or IS,in accordance with the movement of handle 14.

Manual disc I2 is provided with a central notch 2| into which is fitteda pawl 22 mounted on a Common pawl spring 23, and on both sides ofcentral notch 2i are positioned lateral notches 24. Core 25, insidesolenoid I0, is positioned to lift pawl 22, which is made of magneticmaterial, out of notches 2! or 24, as the case may be.

In operation, assuming that the vehicle is proceeding straight-ahead, nocircuits will be energized by the automatic switch. If it is thendesired to set up a right or left signal, handle 14 is moved to right orleft, respectively, and pawl 22 will ride out of central notch 2| andcome to rest in one of the lateral notches 24, and the manual switchwill remain in contact making position, illuminating the lamps selected.Thereafter, when a vehicle turn is made, following the presetting of thesignal, the automatic switch will make contact to either the right orleft lamps, current will pass through solenoid Ill, magnetizing core 25,pulling pawl 22 out of notch 24, and the return spring IE will returnthe handle !4 to neutral position. This will happen irrespective ofwhether the automatic switch energizes the same lamps energized by thehand switch, or the opposite lamps.

However, the same condition does not exist under these twopossibilities. Referring directly to Fig. 3, I have shown a conditionwhere the automatic switch energizes the left hand lamps and the handswitch energizes the right hand lamps. Under these circumstances,presupposing balancing resistor 28 were not used, current equal to theconsumption of the left lamps would invariably flow through solenoid i6,irrespective of current flowing through the right lamps via the handswitch. Under these circumstances, the pawl would pull out, and Fig. 3shows the condition of the circuit immediately after the pawl has beenpulled out of the notch and extended spring I5 is ready to pull thehandle M- to central position.

Under these circumstances, however, balancing resistor 29 simply acts toreduce the current through the right hand lamps by a relatively smallamount, and this resistor may be made equal or substantially equal tothe resistance of solenoid if}, and thus there will be no difference inthe brilliancy of the right or left lamps. It will be noticed that bothlamps will be lit for a fraction of a second, just as long as necessaryfor the manual switch to return to central position. However, I havefound that the lag in the filaments of the lamps is sufficient so thatthe observer cannot actually see that current is flowing through bothlamps. In other words, the return time of the manual switch may be madeso fast that the left hand lamps do not get up to brilliancy before theright hand lamps are extinguished.

A different condition exists, however, when both switches aresimultaneously energizing the same lamps. This condition is shown inFig. 2. Here, the automatic switch is shown energizing the left handlamps, and the manual switch is also shown energizing the left handlamps. Under normal circumstances, and viewing the diagram as ifresistor 20 were left out and no other resistance substituted therefor,it will be seen that the path from source ll through the manual switchto the left hand lamps is a short around release coil iii, and if thiswere a complete short, release coil ill would not operate.

In actual practice, however, I have found that when these devices areused on the actual automotive vehicles, the length of cable plus thecontact resistance of manual brushes IT, IS and l9, may be sufilcient tocause enough current to pass through solenoid ID to operate the releaseof pawl 22. However, I have found that when the leads are quite short,as in many special installations, the resistance drop through the manualswitch may not be suflicient to cause an emphatic release. I thereforesupply a balancing resistor 20, positioned in series with the manualcommon brush l1, thus dividing the current when the same lamps are beingenergized by both switches, so that under any and all circumstancesthere will always be sufiicient current passing through solenoid ID tocause efficient magnetization of core 25.

In actual practice, I have found it satisfactory to utilize a resistor20 with a resistance of a value substantially equal to the D. C.resistance of solenoid l0, thus ignoring the inherent circuitresistance. Under such circumstances, I am always able to utilize aminimum of wire in solenoid l0, and I am able to ensure unfailingoperation of the release latch.

While I have shown resistor 20 as being inserted in series with themanual common brush l1, it is obvious that such a resistor may be placedat any point between the source II and the connection of the manualswitch lateral brushes to lamps 8 and 9. In other words, I do not wishto be limited to the position of the resistor, and furthermore, I do notwish to be limited to any exact value of this resistor, this valuedepending not only on the resistance of release solenoid IB, but alsoupon the resistance which is inherently present in the circuits passingthrough the manual switch.

Iv claim:

1. In a vehicle signalling system, right and left indicator circuits,indicating devices in each of said circuits, a power source, a manualswitch having a power brush and lateral brushes, each of said lateralbrushes being connected to an indicator circuit, a manual member movableto two positions to selectively connect one of said lateral brushes tosaid power brush in each of said positions, resilient means forcentralizing said manual member, means for holding said manual member inthe selected position, electromagnetic means for releasing the hold ofsaid holding means, an automatic switch having a central rush and a pairof lateral indicator brushes, each of said lateral indicator brushesbeing connected to an indicator circuit, an automatic member movable byturning of the steering gear of said vehicle for connecting one of saidlateral indicator brushes to said central brush, in accordance with avehicle turn made, said central brush in said automatic switch beingconnected to said power source through said electromagnetic means, and aresistor in series connection between said power brush in said handswitch and said power source.

2. In a vehicle signalling system, right and left indicator circuits,indicating devices in each of said circuits, a power source, a manualswitch having a power brush and lateral brushes, each of said lateralbrushes being connected to an indicator circuit, a manual member movableto two positions to selectively connect one of said lateral brushes tosaid power brush in each of said positions, resilient means forcentralizing said manual member, means for holding said manual member inthe selected position, electromagnetic means for releasing the hold ofsaid holding means, an automatic switch having a central brush and apair of lateral indicator 1,

brushes, each of said lateral indicator brushes being connected to anindicator circuit, an automatic member movable by turning of thesteering gear of said vehicle for connecting one of said lateralindicator brushes to said central brush; in accordance with a vehicleturn made, said central brush in said automatic switch being connectedto said power source through said electromagnetic means, and a resistorin series connection between said power brush in said hand switch andsaid power source, said resistor having a resistance value substantiallyapproach ing the resistance value of said electromagnetic 5 means.

HERBERT E. METCALF.

